Continuous transverse stub (CTS) arrays are disclosed, for example, in U.S. Pat. Nos. 5,926,077; 5,995,055; and 6,075,494. CTS arrays can be implemented as true-time-delay (TTDCTS) apertures employing parallel plate feeds. Typically there are a relatively large number of rails of varying shapes that are fabricated and assembled together in order to realize the aperture/parallel plate feed assembly.
Most antenna applications require two directive (high-gain, narrow bandwidth) beams, each at a different frequency band. In communication applications, the two beams perform the transmit and receive functions. Conventional dish antennas can perform these functions, but require relatively large swept volumes, which is not desirable for an installation that is adversely affected by it, such as an aircraft. Conventional phased arrays also can perform these functions, but include a fully populated lattice of discrete phase-shifters or transmit/receive elements each requiring their own phase and/or power-control lines. The recurring (component, assembly, and test) costs, prime-power, and cooling requirements associated with such electronically controlled phased-arrays can be prohibitive in many applications. In addition, such conventional arrays can suffer from degraded ohmic efficiency (peak gain), poor scan efficiency (gain roll-off with scan), limited instantaneous bandwidth (data rates), and data stream discontinuities (signal blanking between commanded scan positions). These cost and performance issues can be particularly pronounced for physically large and/or high-frequency arrays where the overall phase-shifter/transmit-receive module count can exceed many tens of thousands elements. In addition, when the transmit and receive frequency bands are widely spaced, two arrays can be required, one to perform the transmit function and one for the receive function.